Rotary embossing machine

ABSTRACT

A rotary embossing machine applies an embossing sheet section on a web of material. The rotary embossing machine comprises an embossing device and a counter-pressure cylinder. The embossing device is provided with an embossing element and the embossing element with a supply roll for the embossing sheet, a transport device and an embossing tool.

Rotary embossing machines of this type are known e.g. from the followingdocuments: U.S. Pat. No. 5,486,254, WO 98 12 051 A1, DE 196 25 064 A1,DE 37 13 666 A1, EP 0 718 099 A2, EP 0 437 794 A2, DE 37 18 048 A1, DE90 04 865 U1.

The invention concerns a rotary embossing machine in accordance with thefeatures of the indepenent claim.

BACKGROUND OF THE INVENTION

These rotary embossing machines are used to apply embossing sheetsections onto an endless material web. The embossing sheet sections aresections of a heat-sealing sheet having structured or smooth surfacesand can also have a hologram and a thermally activatable fusion adhesiveon the rear side. During application thereof, the embossing sheetsection is transferred from the sheet web and glued onto the materialweb or the remaining sheet backing is removed from the glued section.During or after gluing, a pattern can be embossed into the surface ofthe sheet. These machines can also be used to apply holograms ontomaterial webs wherein, in particular, the temperature of the embossingtool and of the embossing sheet should be precisely regulated and thetension of the embossing sheet must be exactly controlled to preventdestruction of the hologram.

The embossing sheet advance, which is usually also an endless sheet,must be exactly controlled for exact positioning of the embossing sheetsections and for minimizing embossing sheet waste. The embossing sheetadvance is usually less than the transport speed of the material web.The location where the embossing sheet section is applied mustcorrespond to the imprint in the material web. Finally, for holograms,the section of the embossing sheet to be embossed must be preciselyoriented relative to the embossing stamp to prevent destruction of thehologram, to transfer it into the correct position, and to fix it on thematerial web.

Conventional rotary embossing machines have the associated problem thatthe transport speed of the embossing sheet is adjusted in order tominimize waste. This is associated with a relatively large degree ofeffort.

It is therefore the underlying purpose of the invention to provide arotary embossing machine with which the embossing sheet and also thematerial web are treated with great care, wherein the transport speed ofthe embossing sheet can be adjusted in a simple fashion.

SUMMARY OF THE INVENTION

This object is achieved with a rotary embossing machine having thefeatures of the independent claim. Advantageous further developments canbe extracted from the dependent claims.

The inventive rotary embossing machine ensures that the material web andalso the embossing sheet provided as an endless web are transported onlyin one direction and do not exert any back and forth motion, i.e. thetransport direction does not change. The embossing device, which rotatesin a direction opposite to that of the counter pressure cylinder,contains at least one embossing unit with each embossing unit having itsown complete supply of embossing sheet for that embossing unit. Theembossing sheet is transported by a transport means provided in theembossing unit such that a new embossing sheet section is continuouslysupplied while minimizing sheet waste. This can be effected in a gentlefashion through slow advance.

The rotary motion of the embossing device imparts a speed to theembossing sheet section which corresponds to that of the material websuch that the section can be easily transferred from the embossing toolto the material web. Directly after transfer of the embossing sheetsection, the embossing sheet is gently further transported and a newembossing sheet section is provided. It is important that the embossingdevice precisely matches the speed of the embossing sheet to the speedof the material web. The embossing sheet itself is at rest in theembossing device during the embossing process.

Further advantages, features and details of the invention can beextracted from the following detailed description of three particularlypreferred embodiments with reference to the drawing. The features shownin the drawing and disclosed in the description and the claims may beessential to the invention either individually or in any arbitrarycombination.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a side view of the inventive rotary embossing machine;

FIG. 2 shows a section II—II in accordance with FIG. 1, of a firstembodiment of an embossing device;

FIG. 3 shows a section II—II in accordance with FIG. 1 of a secondembodiment of an embossing device; and

FIG. 4 shows a section II—II in accordance with FIG. 1 of a thirdembodiment of an embossing device.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a rotary embossing machine, referred to in its entiretywith 10, comprising a machine tool table 12 supporting a rotatablydisposed drive shaft 14 for two embossing devices 16, and with a counterpressure cylinder 18. The drive shaft 14 is coupled to a transmission 20and a drive 22. The other end of the drive shaft 14, which is hollow, isprovided with a suctioning device 24 for suctioning e.g. a waste sheet(described in more detail below). The drive 22 of the embossing device16 may be discontinuous.

FIG. 2 shows a section II—II in accordance with FIG. 1 of a firstembodiment of the embossing device 16 which rotates in the direction ofarrow 68. The embossing device 16 comprises a disc-shaped support 26with a total of four embossing units 28. The embossing units 28 aremutually offset by angles of 900 and uniformly distributed about theperiphery. Each embossing unit 28 has a supply roller 30 for anembossing sheet 32 which is stored as an endless web on this supplyroller 30. The embossing sheet 32 is removed from the supply roller 30by a first transport means 34 and is transported in the direction of atake-up roller 36. A further transport means 38 is provided before thetake-up roller 36 which ensures easy transport of the embossing sheet 32about an embossing tool 40.

The embossing tool 40 is an embossing stamp 42 which is disposed fordisplacement towards and away from the counter pressure cylinder 18. Thetwo transport means 34 and 38 each have a traction station 44 formed bytwo rollers and a device 46 for keeping the tension on the embossingsheet 32 constant. This device 46 comprises e.g. spring-loaded rollerswhich apply a constant tension on the embossing sheet 32.

A heating shoe 48 is located between the transport means 34 and theembossing stamp 42 and heats the embossing sheet 32 to a temperature ofe.g. between 80° and 120° C. Moreover, a sensor 50 is located in theregion of the heating shoe 48 or generally before the embossing stamp 42which scans a registration mark of the embossing sheet 32 in an optical,electronic, magnetic or contacting fashion and which controls thetransport means 34 and optionally the transport means 38.

The embossing stamp 42 can also be heatable and the counter pressurecylinder 18 can be heatable or coolable. The transport direction of thematerial web 52 is indicated by arrow 54. The counter pressure cylinder18 rotates correspondingly in the direction of the arrow 56. Thetransport direction of the embossing sheet 32 is therefore opposite tothe transport direction 54 of the material web 52.

The embossing devices 16 can be displaced and adjusted on the driveshaft 14 in the longitudinal direction thereof. This permits processingof different material webs 52 or of different locations on material webs52. Moreover, the drive shaft 14 can be easily provided with additionalembossing devices 16 which are also fixed thereon for secure mutualrotation therewith.

The material web 52 passes a printer controller (indicated with arrow70) upstream of the embossing stamp 42. This printer mark control 70 orembossing control detects registration marks on the material web 52 andcontrols the embossing stamp 42 and optionally the transport means 34and 38.

In the embodiment of FIG. 3, a central disposal means 58 is providedinstead of a take-up roller 36 into which the waste sheet 60 of eachembossing unit 28 is suctioned and removed via the hollow drive shaft 14and the suction device 24. This embodiment advantageously reduces themass of the embossing device 16 and the embossing units 28 can beprovided with larger supply rollers 30.

In the embodiment of FIG. 4 of an embossing device 16 which also hasfour embossing units 28, the drive of the embossing sheet 32 is realizedvia a transport band 62, in particular a vacuum transport band with thevacuum being provided by vacuum chambers 64 and 66. Moreover, vacuumchamber 64 has a heating means for pre-heating the embossing sheet 32.The waste sheet 60 is also centrally suctioned.

Transfer of electrical energy and of data to the embossing devices 16 iseffected either through slip rings or contract-free through a telemetrytransfer means e.g. from the machine tool table 12 to the drive shaft14.

I claim:
 1. A rotary embossing machine for applying an embossing sheetsection onto a material web, the embossing machine comprising: arotating counter pressure cylinder; and at least one embossing devicerotating in a direction opposite to that of said counter pressurecylinder, said embossing device having at least one embossing unitrotating along with the embossing device, the embossing unit having amutually rotating supply roller for the embossing sheet, at least onemutually rotating transport means for the embossing sheet, and amutually rotating embossing tool.
 2. The rotary embossing machine ofclaim 1, wherein said embossing device comprises an embossing disc withat least one embossing unit distributed about a periphery thereof. 3.The rotary embossing machine of claim 1, further comprising a pluralityof embossing devices disposed on a common drive shaft.
 4. The rotaryembossing of claim 3, wherein said drive shaft is hollow.
 5. The rotaryembossing machine of claim 3, wherein said embossing devices areseparated from each other and have adjustable axial positions on saiddrive shaft.
 6. The rotary embossing machine of claim 1, wherein saidembossing unit is mounted on said embossing device in one of a rigidfashion, a movable fashion, a rotatable fashion, and a pivotal fashion.7. The rotary embossing machine of claim 1, wherein said embossing unitcomprises a heating means for the embossing sheet.
 8. The rotaryembossing machine of claim 1, wherein said embossing tool is heated. 9.The rotary embossing machine of claim 1, wherein said embossing tool isan embossing stamp.
 10. The rotary embossing machine of claim 9, whereinsaid embossing stamp can be displaced.
 11. The rotary embossing machineof claim 1, wherein said embossing unit comprises a vacuum holding meansfor the embossing sheet.
 12. The rotary embossing machine of claim 1,wherein said transport means comprises two tensioning means, disposed oneither side of said embossing tool.
 13. The rotary embossing machine ofclaim 1, wherein said transport means comprises means for keeping atension of the embossing sheet constant.
 14. The rotary embossingmachine of claim 1, wherein said counter pressure cylinder can be atleast one of heated and cooled.
 15. The rotary embossing machine ofclaim 1, wherein said embossing unit comprises a register control forthe embossing sheet.
 16. The rotary embossing machine of claim 15,wherein said register control comprises a sensor for register marks onthe embossing sheet.
 17. The rotary embossing machine of claim 1,wherein said embossing unit comprises a take-up reel means for a wastesheet.
 18. The rotary embossing machine of claim 1, wherein saidembossing device comprises a disposing means for a waste sheet of saidat least one embossing unit.
 19. The rotary embossing machine of claim18, wherein said disposing means is a suctioning means.
 20. The rotaryembossing machine of claim 1, wherein said embossing device has adiscontinuous drive.
 21. The rotary embossing machine of claim 20,wherein said drive comprises at least one of a printer mark control anda web sensor for the material web.
 22. The rotary embossing machine ofclaim 1, wherein said transport means for the embossing sheet is one ofa vacuum transport means and a vacuum transport band.
 23. The rotaryembossing machine of claim 1, wherein a transport direction of theembossing sheet is opposite to a transport direction of the materialweb.
 24. The rotary embossing machine of claim 1, wherein the embossingsheet is at rest in said embossing unit during an embossing process.